Induction generator



March 2, 1954 1. E. GOLDBERG 2,671,130

INDUCTION GENERATOR Filed Aug. 24, 1951 N "x q {N 3; N N t (.9

INVENTOR. ASP/45L E. GOLDBERG such as end- Patented Mar. 2, 1954 near. Goldberg, Bendix'Aviation Fort Lee, NJL, assignorjto Corporation, Tet'erboro, N. 1.,

a corporation of Delaware Application August 24, 1951, SerialNo, 243,561

7 Claims.

The invention relates tofinductio'n generators and more particularly to rate g'enerators of the kind used in servo system's'and computers. I

A servo system using a rate. generator shown and described in Riggs Patent .No. 2,115,036 issued April 26., 1938.. The i-ratesgenerator is driven by a servomotor and provides a voltage corresponding to the speed. of themotor which is combined with a signal from a controller and applied to an amplifier to control the motor. The voltage from the rate generator avoids hunting of the motor. I

Rate generators also are used astacho'meters or speed indicating devices in computer systems where the derived resultis .a ifunctionof the'speed and/or acceleration of the motor driving "the generator. I g

Rate vgenerators of the "kind described usually provide a residual voltage when the generator is at rest because of asymmetrical leakage flux, the end of the air gap between, theflrotor'and In a servo system, this residual voltage may drive the servomo'tor from null. position and cause saturation in a servo amplifier so itive 'tosigthat the amplifier becomes nals from the controller. 1 In a computer system, the residual voltage provides a speed 'signal'when the motor is at rest, Obviously such residual voltagesare undesirabl' V V The main object of the present invention, ist'o substantially eliminate the residual "voltage when the rate generatoris'atfrest.

Another object is to inodify' "the. leakage flux pattern, such as endturnfleakag'e flux'and fringe the air gap, to substantially eliminate residual voltage of thel'rate'generator.

Another obj act is- "to' provide an. induction generator having a magnetic circuit which can be adjusted to compensate ror end-turn leakage flux and fringe flux'to provide a flux pattern which substantially eliminates-residual voltage when the generator is'at'rest. V

The invention compensates a'generator having aistator including a core with windings thereon, a rotor rotatable relative to masts-to and 'closely associated with the coreand' an'eiemencof magnetically permeable mater'i ositioned. adjacent to the statorand arrange ,to.moidify','the leakage flux, such as thefleakage flux i'romthe end-turns of the windings andTithe :ifring'e 'fluxfat the end of the air gap betweenihe core and rotor, to substantially eliminatefres'idualvoltage induced in the windings when the rotor is at rest.

The foregoing and other objects and advantages of the invention .will appear, more fully hereinafter 'i'rom a considerationoi the detailed description which follows, taken together with the accompanying drawingrwlienein onelemboditurn leakage fluxIand'fr-inge flux at mounts bearing in and cited windingslo and iings 21' when rotor vantages mentioned above. eliminate the residual. voltage ings 2:! when. therotor is attest, the flux pattern isomodified by assem-bling tor cap 3i arod-like 7 element- :39 of magnetically permeable material ni'nt bf invention- 18 be expressly understood, however, that the drawing is for the urposes or illustration and description only, and, is "not to be construed "as defining the limits of the invention In the drawing, Figure 1 isa transverse vertical section taken approximately on the line I I of Figure 2 of ja generator unitconstructed "according'to the invention, and Figure 2 a longitudinal vertical section taken "approximately on the line 2 -'2 of Figure 'l'through the axis of the unit.

Referring now to 't'hed-raw'ing for a more detailed descri tion of'th; "generator unit of the present invention, the unit comprises a housing I enclosing a motor 3 drivably-connected toan induction generator "5. (the motor comprises a core I 1 of laminated "materialfhaving windings *9 surrounding the coreand having terminals f l 'l adapted for connection to thef output of an ample fi'er or other suitable power source for energizing the windings. rotonfsisnxedto a'snatt I'4 rotatably supported in "beafrmgs -'|='5, ts in housing I. While'an ,feqtiicfmfotor "is sho wn driving the generator, it should be understood that any other suitable'driving means may be used.

Generator 5 is positioned m'housing i adjacent motor '3 and includes'ja stator having a core n of l'aminatedinateri'al withanydesired number of poles 11a. A rotor 18 ,ofjany suitable kind is fixed to shaft l4 and rotateswithin the core and is spaced from the; poles by {an airgapiil. Windings 20, 2| are wound on thecore and are provided with terminals 22,- 23, res ectively. Terminals 22 of windings ZOa-re adapted'to be connected to an alternating current source "(not shown) to energize't'he windings and terminals 23 of windings M are adaptedto be' connected in a control circuit to provide a voltage corresponding 'to the speed of rota'ti'onof'rotor H or motor 3.

Housing I has an annular shoulder-2 7 abutting core l of motor 3 and-a sleeve-leis receivedwithin the housing and one'ehd of the sleeve engages the other side of core 1-. Theoth'er en'd of sleeve 29 engages core 11 of generator 5 and a-cap it! closesthe end ofhousing I and abuts the other side of core 11. Anex pansibie ringse isreceived withinan annular groove 3'5 in housing 'I and trictionally engages cap st to maintain assembly of'th'e motor and generator-inthehousing. r

The arrangement described is; known the art and leakage fiux from the end-turns of exfrin-ge iflux 'irom "the ends of air'g'ap t3 induces a residuaivoItage wind- 18 .is, at rest with the disad- .To substantially induced in wind-- rotation of said rotor extending inwardly of housing I close to and within windings, 2|. One end of rod 39 is fixed in an aperture 40 in cap 3! and the other end is positioned adjacent to core l1 near the end of the air gap. Element 39 is adjusted relative to core l1 and windings 20, 2| when rotor I8 is at rest by rotating cap 3|, before ring 33 is installed in groove 35, to reduce the coupling of the windings until the residual voltage induced in windings 2i is a minimum. Ring 33 then is installed in groove 35 and frictionally engages cap 3| and holds it against rotation relative to housme I.

The substantially arrangement described eliminates residual voltage of the generator when the rotor is at rest so that the generator is especially adapted for use in a computer of the kind described and in a servo system where the servo motor must be accurately returned to zero posi tion.

Although only one embodiment of the invention has been illustrated and described in detail, it is-to be expressly understood that theinven- .tion is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

I I claim:

1, A generator of the kind described having a stator with excited and output windings thereon, a rotor rotatable relative to said stator, and an element of magnetically permeable material closely associated with said stator and fixedrelw tive thereto and positioned to reduce the coupling of said windings by modifying leakage flux from said excited winding to substantially eliminate residual voltages induced in said output winding when said rotor is at rest.

2. A generator of the kind described having a relatively rotatable rotor and stator, said stator having a core with a pair of windings thereon, one of said windings being adapted for energization by an alternating current source for inducing a voltage in said other winding upon relative and stator, an element of magnetically permeable material closely associated with said stator and fixed relative thereto and positioned to reduce the coupling of said windings by modifying leakage flux from said energized winding to substantially eliminate residual voltages induced in said other winding when said rotor is at restrelative to said stator.

3. A generator of the kind described including a stator having a corewith a plurality of poles and windings thereon, a rotor rotatable relative to said stator and closely associated with said poles, one of said windings being adapted for energization by an alternating current source for inducing a voltage in said other winding upon relative rotation of said rotor and stator, and an element of magnetically permeable material positioned adjacent to said stator and arranged to reduce the coupling of said windings by modifying the leakage flux from the end-turns of said excited'winding and the fringe flux at the end of the air gap between the poles and rotor to sub stantially eliminate residual voltages induced in said other winding when said rotor is at rest.

4. A generator of the kind described having a stator with a core and windings thereon, a rotor rotatable relative to said stator andiclosely associated with said core and forming an air gap therebet'ween one of said windings being adapted for energization by an alternating current source for inducing a voltage in said other winding upon relative rotation of said rotor and stator, a rod-like element of magnetically permeable material extending close to said windings and having one end positioned adjacent the end of said air gap, said element being positioned and arranged to reduce the coupling of said windings by modifying the leakage flux from the end-turns of said excited winding and fringe flux at the end or the air gap to substantially eliminate residual voltages induced in said other winding when said rotor is at rest.

5. A generator of the kind described having a housing with a cap adjustable angularly relative thereto and means for maintaining said cap assembled to said housing and fixed relative thereto after'adiustment, a stator mounted within said housing and including a core with windings thereon, a rotor rotatable relative to said stator and closely associated with said core, one of said windings being adapted for energization by an alternating current source for inducing a voltage in said other winding upon relative rotation of said rotor and stator, and a rod-like element of magnetically permeable material mounted on said cap and extending inwardly of said housing close to said windings and having one end positioned adjacent to said core, said cap being adjusted angularly so that said element is in a position relative to said windings and said core to reduce the coupling of said windings by modifying the leakage flux from said excited winding to substantially eliminate residual voltages induced in said other winding when said rotor is at rest.

6. A generator of the kind described having a housing with a cap adjustable angularly relative thereto and means for maintaining said cap assembled to said housing and fixed relative thereto after adjustment, a stator mounted within said housing and including a core with windings thereon, a rotor rotatable relative to said stator and closely associated with said core and spaced therefrom by an air gap, one of said windings being adapted for energization by an alternating current source for inducing a voltage in said otherwinding upon relative rotation of said rotor and stator, and a rod-like element of magnetically permeable material mounted on said cap and extending inwardly of said housing close to said windings and having one end positioned adjacent the end or said air gap, said cap being adjusted angularly so that said element is in a position relative to said windings and. said core to reduce the coupling of said winding by modifying the leakage .flux from the end-turns of said excited winding and the fringe flux at the end of said air gap to substantially eliminate residual voltages induced in said other winding when said rotor is at rest.

7. A generator of the kind described having a stator, with excited and output windings thereon, a rotor rotatable relative to said stator, and an element of magnetically permeable material closely associated with said stator and fixed relative thereto and positioned to reduce coupling between the windings when said rotor is at rest to substantially eliminate residual voltages induced in said output winding.

ISRAEL E. GOLDBERG.

References Cited in the flle of this patent UNITED STATES PATENTS 

